On Tue, 12 Feb 2013 13:13:03 -0800, Fred Abse <excretatauris@invalid.invalid> wrote:>On Mon, 11 Feb 2013 14:29:37 -0800, mike wrote: > >> A curve tracer is a qualitative measurement device. I use a TEK 7CT1N for >> simple stuff and only drag out the 576 when I gotta have it. I use it >> more for blowing shorts out of NiCd's than for testing transistors. > >The 7CT1 is perhaps mainly a qualitative device. The 576, which I use >regularly, is capable of quite accurate measurements, used correctly. >(Reminder to self, I must dig out the 2N7000 sub-threshold measurements >I did in response to Jim T, and curve fit them)That's been awhile. IIRC I fit a PSpice Level=7 to either your data or Win's... been a long time ;-)> >> >> If you try to make one using a series of fixed measurements and graphing >> them, you get mixed results. I tried that back in the day. The device >> thermal time constants significantly affect the measurement details. > >That's what pulsed measurements are for. I regularly test devices at up to >200 amps, using a 176 pulsed high current fixture, without thermal >problems. > >> >> And the parasitics of the test fixture swamp device parasitics, unless >> you use network analyzer fixturing. > >That applies to measurements generally....Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Curve tracers
Started by ●February 11, 2013
Reply by ●February 12, 20132013-02-12
Reply by ●February 12, 20132013-02-12
On 2/12/2013 1:13 PM, Fred Abse wrote:> On Mon, 11 Feb 2013 14:29:37 -0800, mike wrote: > >> A curve tracer is a qualitative measurement device. I use a TEK 7CT1N for >> simple stuff and only drag out the 576 when I gotta have it. I use it >> more for blowing shorts out of NiCd's than for testing transistors. > > The 7CT1 is perhaps mainly a qualitative device. The 576, which I use > regularly, is capable of quite accurate measurements, used correctly. > (Reminder to self, I must dig out the 2N7000 sub-threshold measurements > I did in response to Jim T, and curve fit them) > >> >> If you try to make one using a series of fixed measurements and graphing >> them, you get mixed results. I tried that back in the day. The device >> thermal time constants significantly affect the measurement details. > > That's what pulsed measurements are for. I regularly test devices at up to > 200 amps, using a 176 pulsed high current fixture, without thermal > problems.Methinks you're applying apples thinking to oranges. If you take a measurement at a fixed operating point, whether it be DC or pulsed, your average junction temperature is likely to be different from what it would be in an analog curve tracer like the 576. All those measurement points are not likely to line up on exactly the same line you'd see with an analog plot. Nothing wrong with that. If you want data at a particular operating point, that's the way to go. If you want a curve tracer, like it says in the subject line, you may not see what you expect.> >> >> And the parasitics of the test fixture swamp device parasitics, unless >> you use network analyzer fixturing. > > That applies to measurements generally. >
Reply by ●February 12, 20132013-02-12
"Joerg" <invalid@invalid.invalid> wrote in message news:ant8q2FtibeU1@mid.individual.net...> Phil Hobbs wrote: >> On 02/11/2013 04:03 PM, Joerg wrote: >>> Phil Hobbs wrote: >>>> Hi, all--I'm looking for a curve tracer. Ideally it would be >>>> USB-powered, and come with software that would make plots and >>>> generate >>>> data files. Nothing too fancy, just I_C and I_B vs V_CE and V_BE, >>>> and >>>> the equivalent for FETs. A plus would be automatic computation of >>>> beta, >>>> V_GSth, Early voltage, and even some of the DC SPICE parameters >>>> like >>>> emitter and base resistance. >>>> >>>> It would be especially nice if it could measure gate current with a >>>> resolution of a picoamp or less. >>>> >>>> Any suggestions? >>>> >>> >>> Quite a niche market, that probably gets expensive: >>> >>> http://c418683.r83.cf2.rackcdn.com/uploaded/BL_765670_e_ver2.pdf >>> >> I found one at Photonics West for $169, distributed by Ana Tek. (For >> Canadians with long memories, this isn't the power supply >> manufacturer >> from Vancouver.) >> >> http://www.anatekcorp.com/test%20equipment.htm . >> >> Doesn't seem to do gate leakage, though. The optimal combination >> might >> be one of these plus a bandaid box made of op amps, to increase the >> measured current by, say, 1E7 times to make the FET look more like a >> BJT. That would confuse its built-in functions completely, I expect. >> >> What I'm using now is a cast-aluminum Bud box with op amps in it, >> that >> generates a nice ramp for V_GS, has a knob for V_DS, and has TIAs for >> I_G and I_D. Works well but is a bit of a pain, and has no data acq. >> >> I could put something like that on the front of a Labjack (Joerg's >> fave). That would be a bit more dough, but I'll be needing to do a >> half >> dozen protos with data acquisition in the next few weeks anyway, so I >> can amortize the s/w labour over my gizmo and the client's work. (I >> hate charging clients for building libraries.) >> >> A standalone unit would be a lot nicer though. >> > > Hey, doesn't one of your kids want to get his hands dirty with some > software work? If you charge the client a lower rate for that work he > could still sock away a lot of money towards his first souped-up > TransAm > with mag wheels and all that :-) > > If it's any comfort I'll have to design some radio circuitry soon and > build (yuck ...) several prototypes. Will use Labjacks again, mainly > because those come with a copy of a SCADA software to make life a bit > easier for SW-challenged guys like me. I just hope the garage ain't so > cold anymore once I get to do the boxes. But I don't envy you guys out > there right now, had a teleconference this morning and one guy is on > Long Island, snowed in. >He must be on the north shore in Suffolk county. It was like a 3rd world country out there on Monday. 33" somewhere, I think Farmingville. We still have people MIA at work, snowed in. The plows never got down their streets. I'm further east, still got 19", but like Phil only took an hour or two to clean up. Cheers
Reply by ●February 12, 20132013-02-12
Martin Riddle wrote:> "Joerg" <invalid@invalid.invalid> wrote in message > news:ant8q2FtibeU1@mid.individual.net... >> Phil Hobbs wrote: >>> On 02/11/2013 04:03 PM, Joerg wrote: >>>> Phil Hobbs wrote: >>>>> Hi, all--I'm looking for a curve tracer. Ideally it would be >>>>> USB-powered, and come with software that would make plots and >>>>> generate >>>>> data files. Nothing too fancy, just I_C and I_B vs V_CE and V_BE, >>>>> and >>>>> the equivalent for FETs. A plus would be automatic computation of >>>>> beta, >>>>> V_GSth, Early voltage, and even some of the DC SPICE parameters >>>>> like >>>>> emitter and base resistance. >>>>> >>>>> It would be especially nice if it could measure gate current with a >>>>> resolution of a picoamp or less. >>>>> >>>>> Any suggestions? >>>>> >>>> Quite a niche market, that probably gets expensive: >>>> >>>> http://c418683.r83.cf2.rackcdn.com/uploaded/BL_765670_e_ver2.pdf >>>> >>> I found one at Photonics West for $169, distributed by Ana Tek. (For >>> Canadians with long memories, this isn't the power supply >>> manufacturer >>> from Vancouver.) >>> >>> http://www.anatekcorp.com/test%20equipment.htm . >>> >>> Doesn't seem to do gate leakage, though. The optimal combination >>> might >>> be one of these plus a bandaid box made of op amps, to increase the >>> measured current by, say, 1E7 times to make the FET look more like a >>> BJT. That would confuse its built-in functions completely, I expect. >>> >>> What I'm using now is a cast-aluminum Bud box with op amps in it, >>> that >>> generates a nice ramp for V_GS, has a knob for V_DS, and has TIAs for >>> I_G and I_D. Works well but is a bit of a pain, and has no data acq. >>> >>> I could put something like that on the front of a Labjack (Joerg's >>> fave). That would be a bit more dough, but I'll be needing to do a >>> half >>> dozen protos with data acquisition in the next few weeks anyway, so I >>> can amortize the s/w labour over my gizmo and the client's work. (I >>> hate charging clients for building libraries.) >>> >>> A standalone unit would be a lot nicer though. >>> >> Hey, doesn't one of your kids want to get his hands dirty with some >> software work? If you charge the client a lower rate for that work he >> could still sock away a lot of money towards his first souped-up >> TransAm >> with mag wheels and all that :-) >> >> If it's any comfort I'll have to design some radio circuitry soon and >> build (yuck ...) several prototypes. Will use Labjacks again, mainly >> because those come with a copy of a SCADA software to make life a bit >> easier for SW-challenged guys like me. I just hope the garage ain't so >> cold anymore once I get to do the boxes. But I don't envy you guys out >> there right now, had a teleconference this morning and one guy is on >> Long Island, snowed in. >> > He must be on the north shore in Suffolk county. It was like a 3rd world > country out there on Monday. 33" somewhere, I think Farmingville. > We still have people MIA at work, snowed in. The plows never got down > their streets. > I'm further east, still got 19", but like Phil only took an hour or two > to clean up. >He lives in north of East Setauket, I think that's 6mi north of Farmingville. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●February 12, 20132013-02-12
On Tue, 12 Feb 2013 20:00:29 -0500, "Martin Riddle" <martin_rid@verizon.net> wrote:> >"Joerg" <invalid@invalid.invalid> wrote in message >news:ant8q2FtibeU1@mid.individual.net... >> Phil Hobbs wrote: >>> On 02/11/2013 04:03 PM, Joerg wrote: >>>> Phil Hobbs wrote: >>>>> Hi, all--I'm looking for a curve tracer. Ideally it would be >>>>> USB-powered, and come with software that would make plots and >>>>> generate >>>>> data files. Nothing too fancy, just I_C and I_B vs V_CE and V_BE, >>>>> and >>>>> the equivalent for FETs. A plus would be automatic computation of >>>>> beta, >>>>> V_GSth, Early voltage, and even some of the DC SPICE parameters >>>>> like >>>>> emitter and base resistance. >>>>> >>>>> It would be especially nice if it could measure gate current with a >>>>> resolution of a picoamp or less. >>>>> >>>>> Any suggestions? >>>>> >>>> >>>> Quite a niche market, that probably gets expensive: >>>> >>>> http://c418683.r83.cf2.rackcdn.com/uploaded/BL_765670_e_ver2.pdf >>>> >>> I found one at Photonics West for $169, distributed by Ana Tek. (For >>> Canadians with long memories, this isn't the power supply >>> manufacturer >>> from Vancouver.) >>> >>> http://www.anatekcorp.com/test%20equipment.htm . >>> >>> Doesn't seem to do gate leakage, though. The optimal combination >>> might >>> be one of these plus a bandaid box made of op amps, to increase the >>> measured current by, say, 1E7 times to make the FET look more like a >>> BJT. That would confuse its built-in functions completely, I expect. >>> >>> What I'm using now is a cast-aluminum Bud box with op amps in it, >>> that >>> generates a nice ramp for V_GS, has a knob for V_DS, and has TIAs for >>> I_G and I_D. Works well but is a bit of a pain, and has no data acq. >>> >>> I could put something like that on the front of a Labjack (Joerg's >>> fave). That would be a bit more dough, but I'll be needing to do a >>> half >>> dozen protos with data acquisition in the next few weeks anyway, so I >>> can amortize the s/w labour over my gizmo and the client's work. (I >>> hate charging clients for building libraries.) >>> >>> A standalone unit would be a lot nicer though. >>> >> >> Hey, doesn't one of your kids want to get his hands dirty with some >> software work? If you charge the client a lower rate for that work he >> could still sock away a lot of money towards his first souped-up >> TransAm >> with mag wheels and all that :-) >> >> If it's any comfort I'll have to design some radio circuitry soon and >> build (yuck ...) several prototypes. Will use Labjacks again, mainly >> because those come with a copy of a SCADA software to make life a bit >> easier for SW-challenged guys like me. I just hope the garage ain't so >> cold anymore once I get to do the boxes. But I don't envy you guys out >> there right now, had a teleconference this morning and one guy is on >> Long Island, snowed in. >> >He must be on the north shore in Suffolk county. It was like a 3rd world >country out there on Monday. 33" somewhere, I think Farmingville. >We still have people MIA at work, snowed in. The plows never got down >their streets. >I'm further east, still got 19", but like Phil only took an hour or two >to clean up. > >Cheers >It rained here yesterday. Low 60's daytime... but it did go down to freezing last night... the swimming pool pump came on automatically to prevent pipe freezing ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●February 12, 20132013-02-12
"Joerg" <invalid@invalid.invalid> wrote in message news:ao079aFj92vU1@mid.individual.net...> Martin Riddle wrote: >> "Joerg" <invalid@invalid.invalid> wrote in message >> news:ant8q2FtibeU1@mid.individual.net... >>> Phil Hobbs wrote: >>>> On 02/11/2013 04:03 PM, Joerg wrote: >>>>> Phil Hobbs wrote: >>>>>> Hi, all--I'm looking for a curve tracer. Ideally it would be >>>>>> USB-powered, and come with software that would make plots and >>>>>> generate >>>>>> data files. Nothing too fancy, just I_C and I_B vs V_CE and >>>>>> V_BE, >>>>>> and >>>>>> the equivalent for FETs. A plus would be automatic computation >>>>>> of >>>>>> beta, >>>>>> V_GSth, Early voltage, and even some of the DC SPICE parameters >>>>>> like >>>>>> emitter and base resistance. >>>>>> >>>>>> It would be especially nice if it could measure gate current with >>>>>> a >>>>>> resolution of a picoamp or less. >>>>>> >>>>>> Any suggestions? >>>>>> >>>>> Quite a niche market, that probably gets expensive: >>>>> >>>>> http://c418683.r83.cf2.rackcdn.com/uploaded/BL_765670_e_ver2.pdf >>>>> >>>> I found one at Photonics West for $169, distributed by Ana Tek. >>>> (For >>>> Canadians with long memories, this isn't the power supply >>>> manufacturer >>>> from Vancouver.) >>>> >>>> http://www.anatekcorp.com/test%20equipment.htm . >>>> >>>> Doesn't seem to do gate leakage, though. The optimal combination >>>> might >>>> be one of these plus a bandaid box made of op amps, to increase the >>>> measured current by, say, 1E7 times to make the FET look more like >>>> a >>>> BJT. That would confuse its built-in functions completely, I >>>> expect. >>>> >>>> What I'm using now is a cast-aluminum Bud box with op amps in it, >>>> that >>>> generates a nice ramp for V_GS, has a knob for V_DS, and has TIAs >>>> for >>>> I_G and I_D. Works well but is a bit of a pain, and has no data >>>> acq. >>>> >>>> I could put something like that on the front of a Labjack (Joerg's >>>> fave). That would be a bit more dough, but I'll be needing to do a >>>> half >>>> dozen protos with data acquisition in the next few weeks anyway, so >>>> I >>>> can amortize the s/w labour over my gizmo and the client's work. >>>> (I >>>> hate charging clients for building libraries.) >>>> >>>> A standalone unit would be a lot nicer though. >>>> >>> Hey, doesn't one of your kids want to get his hands dirty with some >>> software work? If you charge the client a lower rate for that work >>> he >>> could still sock away a lot of money towards his first souped-up >>> TransAm >>> with mag wheels and all that :-) >>> >>> If it's any comfort I'll have to design some radio circuitry soon >>> and >>> build (yuck ...) several prototypes. Will use Labjacks again, mainly >>> because those come with a copy of a SCADA software to make life a >>> bit >>> easier for SW-challenged guys like me. I just hope the garage ain't >>> so >>> cold anymore once I get to do the boxes. But I don't envy you guys >>> out >>> there right now, had a teleconference this morning and one guy is on >>> Long Island, snowed in. >>> >> He must be on the north shore in Suffolk county. It was like a 3rd >> world >> country out there on Monday. 33" somewhere, I think Farmingville. >> We still have people MIA at work, snowed in. The plows never got down >> their streets. >> I'm further east, still got 19", but like Phil only took an hour or >> two >> to clean up. >> > > He lives in north of East Setauket, I think that's 6mi north of > Farmingville. >Yea, abouts. That�s up by Port Jefferson, on the north shore. They had like 8" Friday evening, where the south shore was just changing over from rain to snow. It was heavy stuff. I heard they had Snow Blowers clearing the 495 expressway. and I seen the Snow Blowers clearing the shoulders on the parkways this evening. Getting ready for the next two storms, 5" Wednesday and More to come on the weekend. Too bad theres no ski resorts here ;( Cheers
Reply by ●February 13, 20132013-02-13
On Mon, 11 Feb 2013 17:25:17 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:> >> Hey, doesn't one of your kids want to get his hands dirty with some >> software work? If you charge the client a lower rate for that work he >> could still sock away a lot of money towards his first souped-up =TransAm>> with mag wheels and all that :-) >> > >Brr. My son is _not_ "going to drive me to drinkin'" if I can help it,=20 >but anyway that wouldn't be his style. He's busy writing Arm Cortex M3=20 >firmware at the moment, but since he's learning C at the same time, he=20 >isn't fast at it yet. (He did get a task switcher working, using a=20 >linked list of tasks handled by the systick interrupt handler.)Hey it may be a bit basic, but it works. It is an adequate approach for very simple rate monotonic schedulers but the linked list time will start to hurt if things get complicated and crowded schedule wise. He needs to separate the switcher from the task manager. Then schedule time for the task manger as a task.> >> If it's any comfort I'll have to design some radio circuitry soon and >> build (yuck ...) several prototypes. Will use Labjacks again, mainly >> because those come with a copy of a SCADA software to make life a bit >> easier for SW-challenged guys like me. I just hope the garage ain't so >> cold anymore once I get to do the boxes. But I don't envy you guys out >> there right now, had a teleconference this morning and one guy is on >> Long Island, snowed in. >> > >My wife and I spent a very pleasant hour or so on Saturday, digging out=20 >from 18-24 inches of pretty light snow. It was heavier near the road=20 >where the plough had been, of course, but no worries. Bright sunshine,=20 >well above freezing, sun melting the last little bits of snow left=20 >behind on the driveway. > >Cheers > >Phil Hobbs
Reply by ●February 13, 20132013-02-13
On Tue, 12 Feb 2013 11:54:38 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:> >>> Hey, doesn't one of your kids want to get his hands dirty with some >>> software work? If you charge the client a lower rate for that work he >>> could still sock away a lot of money towards his first souped-up =TransAm>>> with mag wheels and all that :-) >>> >>> If it's any comfort I'll have to design some radio circuitry soon and >>> build (yuck ...) several prototypes. Will use Labjacks again, mainly >>> because those come with a copy of a SCADA software to make life a bit >>> easier for SW-challenged guys like me. I just hope the garage ain't =so>>> cold anymore once I get to do the boxes. But I don't envy you guys =out>>> there right now, had a teleconference this morning and one guy is on >>> Long Island, snowed in. >> >> I was expecting a visit from a Pratt&Whitney guy. He lives near >> Hartford CT. His driveway is 400 feet long and maybe 40 feet wide. I >> calculated that he had roughly 400 tons of snow in the driveway. > >And that he could probably afford a plough guy, or two. ;) > >> >> He rescheduled. >>Likely they would also have to plough 1/2 mile or more street just to get to his driveway. ?-)
Reply by ●February 13, 20132013-02-13
On Mon, 11 Feb 2013 21:21:55 -0500, "Michael A. Terrell" <mike.terrell@earthlink.net> wrote:> >tm wrote: >>=20 >> This might be worth $24 to explore. Needs +/- 15 volts and a XY scope. > > > $2 less in kit form. I have 25 new Integrated power designs >SRW-65-4006 switching power supplies with +/=3D 15V outputs. > > >http://034262c.netsolhost.com/wp-content/uploads/2011/06/SRW-65%20Specs.=pdf That is a nice old time experimenters supply. Are they available?> >and a small pile of used open frame Lambda, Power One etc linear >supplies. > > >> =http://www.ebay.com/itm/140547987228?ssPageName=3DSTRK:MEWAX:IT&_trksid=3D= p3984.m1423.l2649> >at lest they give you the schematic. :)
Reply by ●February 13, 20132013-02-13
On Mon, 11 Feb 2013 14:29:37 -0800, mike <ham789@netzero.net> wrote:>On 2/11/2013 10:42 AM, Phil Hobbs wrote: >> Hi, all--I'm looking for a curve tracer. Ideally it would be >> USB-powered, and come with software that would make plots and generate >> data files. Nothing too fancy, just I_C and I_B vs V_CE and V_BE, and >> the equivalent for FETs. A plus would be automatic computation of =beta,>> V_GSth, Early voltage, and even some of the DC SPICE parameters like >> emitter and base resistance. >> >> It would be especially nice if it could measure gate current with a >> resolution of a picoamp or less. >> >> Any suggestions? >> >> Cheers >> >> Phil Hobbs >> >You're asking a LOT. > >A curve tracer is a qualitative measurement device. >I use a TEK 7CT1N for simple stuff and only drag out the 576 >when I gotta have it. I use it more for blowing shorts >out of NiCd's than for testing transistors.I use big honking caps or car batteries for that.> >If you try to make one using a series of fixed measurements >and graphing them, you get mixed results. I tried that back in the day. >The device thermal time constants significantly affect the measurement >details.That is why they added pulse mode measurements, so you could see it both ways.> >And the parasitics of the test fixture swamp device parasitics, unless =you>use network analyzer fixturing.Even then.> >Picoamps to amps is a wide dynamic range and will require some serious >attention to range switching. > >Not saying it can't be done, just that it's not nearly as simple as it=20 >sounds. >Agreed on the range switching issues. Maybe just use different test equipment. ?-)
